Echoing what Heikki said, I personally haven't used any of the site generators mentioned. However the solution does need to be a simple git checkout and with minimal dependencies you can make updates. I've tried to get the current site doc generated a few times without much luck in generating some of the pages. So definitely simplicity rules.
I believe github uses Jekyll and it supports the markdown syntax that is easy to understand and used on github. But I haven't used it so can't vouch for its ease of use or popularity.
